The balanced reaction equation for the reaction between CH₃OH and Oâ‚‚ isÂ
            2CH₃OH(l) + 3O₂(g) → 2CO₂(g) + 4H₂O(l)
Initial moles     12         24
Reacted moles  12         18
Final moles      -          6        12        24
Â
The stoichiometric ratio between CH₃OH and O₂ is 2 : 3
Hence,
  reacted moles of O₂ = reacted moles of CH₃OH x (3/2)
                   = 12 mol x 3 / 2 Â
                   = 18 mol
All of CH₃OH moles react with O₂.
Hence, the limiting agent is CH₃OH.Â
Excess reagent is Oâ‚‚.
Amount of moles of excess reagent left = 24 - 18 mol = 6 mol
                      Â